Alternating-current motor.



I PATENTBD OCT. 23, 1906.

G. A. ABLBTT. ALTERNATING CURRENT MOTOR.

' APPLIOATION FILED JULY 30, 1903.

2 SHEETS-SHBBT'L Fig! , UNITED STATES PATENT OFFICE. I y

CHARLES A. ABLETT, OF- SCH-ENECTADY; "Ii-EW YORK. ASSiGrroii-To GEN--- naAL' ELECTRIC. CQMBANY, A co uftuttriou or roux,

ALTEBNATIY'NGFIGUBHEI'IVT Maren.

Specification-.of'fitters Pat ent. Application filed m 36, iaca seen some;

To all whom it may concern;- I

Be it known that 1, CHARLnsA; ABLErr,la1 subject of the King of Great Britain, residing at Schenectady, in the county of Sehenec tady and State of New York,- have invented certain new and useful Improvements in Alternating-Current Motors, of which vthe following is a specification.

This invention relates to alternating-cur-.. rent electric motors. Motors of this class'inwhich commutators are employed. have not come into practical use, largely on'accou'nt ofthe destructive sparking w 'ch occurs at the commutator. i t

The object of my invention is to so reduce such sparking thatit will bepractically inconsiderable. I accomplish this result by reducin the self-ind'uctionof each coil of the secon ary winding and the resultant magnetic flux through it to a at the time at which its circuit is broken at the conimutator. This may be accomplished by con-- i structing the core of the primary circuit with polar projections and so proportioning the width and pitchof saidpolar projections and the width of the coils of the secondary winding that a position may be found in which the self-induction of the coil of the secondary oor sparking at the break. This condition may by constructing a cupying that osition and the magnetic flux through it, be so reduced that ts circuit may be broken without causing any serious be produced in the case of a repulsion-motorprimary-with polar projections and making the coils of the secondary of a width not greater than the distance between said-projections, the circuit of each coil 'terial to screen being broken in the position 1n which it incloses the fewest ma etic lines. The action may be assisted by p acing between the polar projections a-ringlor plate of conducting mat e secondary coils when between the projections from the magnetic in fluence of theprimary.

' I have found it advantageous tohave selfinduction of the secondary circuits of a repulsion-motor less in certain positions-with relation to the primary when the motor is startthan it is when the motor is running. a

t is therefore a further-object of my invention. to provide a motor in which these condi- -t ions will be realized. This I do by constructing a motor the secondary circuits of which have the proper self-induction for one condidicated by'dotted constitute the primary core.

ao tafiatpfaeditgi etmrtisteamy than ging such SQlf+iI1diItl0ii to'meet the other cons'diti'om chaiigfiinself induction "of the secondary circuits maybe-.brought; about by changing the 'reluctance of themagnetic circuitot' the secondary Ref 'to -he-accompanying-drawings, I

. Figure zlris a side elevation, partly 'insection, of a' repuls on-motor embed with parts broken away andshownpartly in .secticnandwithanalternating-current source of,. supply (shown in diagram) connected tion, of the? pulley end of. the motor, showing a. means for changing the self induct-i'cn of the secondary circuits, while Fig. 4' is a development of the secondary member of the motor, the location of the lpplar projections being in-- es and ftheposition with relation'to said projections of certain portions olt1 myinduction-changing device being also s own. 1

Referring to the figures,- C is the frame 'of i the machine,'us'ually of cast-iron, having dovetailed. slots for receiving appropriate projections from the 'laminaticns l, which The laminationsconstituting the polar projections 12 are in this case stamped in the same piece with those constituting the remainder of the primary core and are held in place by the usual clamping bolts and rings. The pn'marycoils -c may be slid onto the projections after the machine has been assembled, and they are heldin position by the flux-screens h, which may be of a construction similar to the ordinary antihunting devices-such, for instance, as shown in Patent No. 650,677, issued to. Geisenhoner and Knight, May 29 1 900. These screens extend between the polar projections and are securedin place by engagement with the notches in said projections, as shown. v v The construction. of the primary thus far described is not new and may be varied as circumstances require. The coils c are connected In any suitable relation to produce north and south poles alternately about the "frame and are connected to the alternating source of supply F, as indicated inFig. 2, the leads f and'g being connected to tlle'terminals of coils 0. Upon the secondary'meniber S, which may be constructed in any well- IOC ,Each of said coils is of approximately the same width as a polar projection p, and it will be noted that the width of the polar projection is less than one-half of the polar pitch.

At certain times, therefore, the coils will lie between the polar projections and will be entirely removed from beneath them. In this. position these coils'are removed from inductiverelation to the primary, and their magnetic circuits are practically broken, thereby reducing the magnetic flux through them and also their self-induction to a minimum. The flux-screens h assist the action by choking back any leakage'fiux which might tend to flow between the poles.

The width of each secondary coil should bev not greater than the distance between the polar projections, and if its width is somewhat less than that distance the action will be improved, because the current in the secondary coil will have an opportunity to die down after the coil has passed out of induc in the same slot.

tive relation to the primary circuit. The coils are wound in two-phase relationthat is to, say, in two sets-one of which is displaced ninety degrees -from the other, the sides of adjacent coils of one set being placed Any other suitable arrangen'ient of coils might be used however. From the terminals of each of the secondary coils leads are brought out and connected to segments of the commutator D. Bearing' upon the commutator D are brushes 5, which are so proportioned and placed as to shortcircuit each oi the secondary code when it is .in operativerelation to the primary and to open the circuit of said coil when it lies between the polar projections. In this case the brushes are of sufficient width to cover two commutator-segments. When the width of each coil is less than the distance between projections, the operation is improved if the rushes are so set that the circuits of the coils will be broken after the coils have remained between the projections for a short interval, thus giving the current a chance to die down before the circuit is broken, and I have so shown them in. the drawings. Although not shown in the drawings, it. will be understood that there will be a brush for each polar projection. H is a rocker-arm of any suitable type, the supporting means for the brush shown being omitted, as it would merely com heats the drawings without aiding in the: lustration of my invention.

Therelative positions. of the parts as the various secondary coils move into and out of action and their circuits are made and broken my be understood by reference to the coils w y, andz in Figs. 1 and 4. the. direction ofv rotationbeing as indicated by thearrows. The coil y lies directly under a polar projection and has not yet been short-circuited, for, as is well known, the axis of the coil should be at an angle to the polar line when its circuit is completed. The axis of the coil 2 lies'at an angle with the polar line. The coil is short-circuited and is in inductive relation to the primary, being still under the polar projection. It is therefore in operative condition. The coil as has just passed out of inductive relation to the primary, but its circuit is still closed and remainsso for a short interval after the coil-has come between the projections in order to allow the current-to die down before the circuit'is broken. A small further movement of the secondary member S'opens the circuit of coil :1: and closes the circuit of coil y, the axis of the latter then being at an angle to the polar line, and the circuit of the coil 2 remains closed. Continued movement of the secondary member causes succeeding secondary coils to be brought into and out of action in a similar manner. Similar operations take place at each of the polar projections.

I will now describe my device for varying .It is best shown in Fig. 3. The secondary primary, as shbwn. machine-frame has at. each polar projection an arm A, having a slot 2, in which is adapted to slide a guide-piece secured to the U-shaped mass M of magnetic material, the masses M being adapted to, embrace the extended portions of the secondary coils. Sleeved upon suits should be of non-magnetic material,) to which are rigidly secured the various masses M. Ring R is slidable upon shaft N through such distance as is necessary-to cause the masses M to approach and reeede from the secondary coils sufficiently to produce the desired change in self-induction of said coils, suchv movement of the ring being brought about by means of links, as m, located. on each side of the shaft N, said links being pivoted to ring R and also to the arms of an actuating-lever L, which is pivoted at q in the pulley-bearing G. Movement. of the handle of the lever L toward and away from the frame of the machine will cause the desired movements of the masses M, as described. Care should be taken to so mount the masses M that no considerable amount of the primary flux will pass through them. This may be done by making the air-gaps between said massesand the primary and secondary cores considerably greater at all times than the air- .gap between the primary and secondary members, as will be-w-ell understood. The proportions of the masses M shouldrbe such as to produce the desired induction in=the t given case.

coils are wound so as to extend beyond the. 5

The end plate E of. the

the self-induction of the secondary circuits.

the shaft N is a ring R, (which for best re- By referringto- Fig. 4 the winding of the scccndary memberwill be 7 Land also the relative positions of the brushes.

" and the char projections.

more plainly seen The relative location of t e masses M is'also shown inthis fig- .u re. It'will be noted that these masses are located in ine with the polar projections, for.

, while it is desired that the coils of the secondary-winding shall be under the influence of these masses when the motor is running, yet when the coils lie under the polar projections that is, when they are in inductive relation to the primary. it is not desirable at any time that coils'lying between 'the'poles-should have self-induction, and in the construction shown'coils in this position are not aiiected. The direction of rotation i ofthe secondary member is indicated in this figureby the arrow.

The motor shown may be considered as constructed to give the appropriate conditions-for either the starting or running operation, since it be readily done by one skilled in the art. In

' the preceding description the motor was assumed to be constructed to meet starting conditions and'a device was described for increasing the self-induction of the secondary coils to that value required to meet the run- Bing-condition.

. have been considered as constructed to meet without any forming the masses M- of solid. conducting material instead of laminated magnetic ma- ..terial.

vIn accordance with the patent statutes .1 have. described the principle of operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof; but I desire to have it understoodthat the apparatus shown in the drawings is only illustrative and that the invention may be carried out by other means" than the Specific embodiment which I have shown.

What I claim is. new, and desire to secure by Letter Pate at of the United States, is- 1'. The combination of a primary core, a

primary winding thereon, an alternating source of supply connected thereto, a second- 'ary core, 001

s constituting a secondary winding in which currents are induced by said rimary winding, a commutator connecte to said, secondary winding, and brushes bearing on said commutator arranged to 0 on an close the circuits of said coils, the W ole being so proportioned and constructed that the is a matter of proportioning theparts to produce the proper self-induction in the ,secondary'coils for the given case,- as will- Themotor might, however,

of running, in which case a' structural change other than than one-half onda circuit of each of said coils will be broken when its self-induction and the magnetic flux through it is a minimum.

2. The combination of aprimary core having polar projections, a primary winding upon said core, an alternating source of sup; ply connected thereto, a secondary'core, e01

constituting a secondary winding in which I currents are induced by said primary wind- "in ,each of said coils being less in width than the distance between polar. projections, a

commutator connected to said, secondary winding, and brushes-bearing upon said. commutator arranged to open. and close the circuits of said coils, the said brushesabeing so ositioned that the circuit of each of said coils-will be broken when it lies between said polar projections. 1 7 3. he combination of a primary core having polar projections, flux-screens between said polar projections, upon said core, an alternating source of supply connected thereto, a secondary core, COllS constituting a secondary winding in which currents are induced by said primary winding, each of said coils being less in width than the distance between polar projections, a

commutator connected to said secondary winding, and brushes bearing upon said commutator arranged. to open; and close the circuits of said coils, the said brushes being so positioned that the. circuit of each of said 'coils will be brokenwhile it lies between said rojections. he combination of a primary core-having polar projections, a primary winding polar 4.

a primary winding.

upon said core, an alternating source of sup.

between polar projections,'

a commutator connected to said secondary winding,

cuits of said coils, the whole being so'constructed and arranged that the circuit of each of said coils is broken an interval oftime after it has passed between said projections.

5. The combination of a primary core having polar projections which width, are less of the polar pitch, a primary winding-upon said core, a secondary core, a sec: winding thereon comprising coils each of which is of approximately the same width as one of said'polar projections, a commutator connected to said secondary winding, and brushes bearing u on said commutator arranged to open an close the circuits of said coils, the said brushes being so positioned that the circuit ofeach of said coils will. be

i and brushes bearing upon said com-- mutator arranged-t0 open and close the cirbroken when it incloses the least magnetic 6. The combination ofap Q than one-half oi the polar pitch, a primary winding upon said core, a secondary core and a secondary winding thereon com rising coils each of which is of approximated; the same width as one of said polar projections, a commutator connected to said secondary winding, and brushes bearing upon said commutator arranged'to open and. close the circuits of said-coils, the Whole being so constructed and arranged that the circuit of each of said coils will be broken when it lies between said projections.

7. The combination of a primary core having polar projections which in width are less than onevhalf of the polar pitch, a primary winding upon said core, 'a secondary core. a secondary winding'thereon comprising coils each of which is of approximately the same width as one of said polar projections, a commutator connected to said secondary wind-- ing, and brushes bearing upon said commutator arranged to open and close the circuits of said coils, the said brushes being so positioned that the circuit of each of said coils will be broken an interval of time after it has passed between said projections.

8. Thecombination of a primary core hav ing polar projections-which in width are less than onealf of the polar pitch, a primary winding upon said core, a secondary core, a

secondary winding thereon comprising individual coils each of which is of approximately the same width as one of said polar projecjections, a commutator connected to said coils, and brushes bearing on said commutator and arranged to close the circuits of said coils when they are in operative relation to said polar projections and to open said circuits when the coils lie between said polar projections.

9. The combination with a. motor,-re uiring different self-induction in its'seco'n ary circuits for starting from that required for running of a member in inductive relation to said secondary circuits"- and movablerelw' tively thereto and adapted to vary byits movement th'eself-induction of said circuits.

10. The combination. of a motor conj structed to have suitable self-induction in its secondary circuits for the condition of starting, and a member in inductive relation to' to said secondary and movable relatively thereto and adapted to'in'crease by its movemerit the self-induction of "said secondary circuits to a point at which the best running condition is obtained.

- 11. In an alternating-current motor, a stationary primary core, a primary winding thereon, a rotary secondary core, a secondary winding carried thereby, and means for changing the reluctance of the magnetic circuit of the secondary winding. whereby the sell-induction oi the secondary winding is varied. 1

12. The combination of a primary core, a primary winding thereon, a secondary core, a secondary winding thereon, masses of magnetic material, and means for causing said masses to approach and recede from said secondary winding. 13. The combination of a primary core, a primary winding upon said core, a secondary core, coils thereon comprising a second winding, and means for changing the sel induction of said coils at that time only when they are in inductive relation tosaid primary winding.

1.4. The combination of a primary core having polar projections, a primary winding on said core, a secondary core, coils thereon, masses of magnetlc material, and means for causing said masses to approach and recede from the coils which lie under said polar projections.

15. The combination of a primary core having polar projections, a prima winding on said core, a secondary core, coi s thereon extending beyond the primary core, masses of magnetic material, and means for causing said masses to approach and recede from the extended portions of those coils which lie under said polar projections.

16. The combination of a primary core having polar projections, a prima winding on said core, a secondary core, coi s thereon extending beyond the primary core, masses of ma etic material adapted to embrace the exten ed portions of said coils, and

for. causing said masses to approach and recedev from said extended portions of those coils which lie under said polar projections.

In witness whereof I have hereunto satiny hand this 28th day ofJuly, 1903 CHARLES A. ABIETT Witnesses:

BENJAMIN B. HULL, Hum: Osman. 

